CN1809770A - Method for producing multilayer optical device - Google Patents

Abstract

A film of aluminum 2 is formed on a glass substrate (BK7) 1 by vacuum evaporation, and a multilayer optical thin film 3 is formed by an ion sputtering method on this aluminum film 2 . Afterwards, such a member is cut into small pieces by means of dicing, and the aluminum 2 is then etched by a sodium hydroxide solution, so that the glass substrate 1 and the multilayer optical thin film 3 are separated. When the aluminum thickness exceeds 90 nm, clouding occurs in the multilayer optical thin film 3 , and when the aluminum thickness is less than 10 nm, the separation of the glass substrate and multilayer optical thin film cannot be performed cleanly. Accordingly, the aluminum thickness is set in a range of 10 to 90 nm.

Description

Make the method for multilayer optical device

Technical field

The present invention relates to a kind of method that the multilayer film optical element that forms by the stacked film of being made up of the material with different refractivity is made.

Background technology

By the stacked film of forming by material with different refractivity and utilize the interference of light of the boundary reflection of these films to have that certain optical properties is construed to as the optical element that filters be a kind of multilayer film optical element, and be used in the interference filter etc.

This multilayer film optical element has following structure, in this structure, film with nonmetal optics material of different refractivity is superimposed upon in the substrate of being made up of glass etc. in succession, and the film that generally forms these nonmetal optics materials in succession by vacuum evaporation in the substrate of compositions such as glass forms this multilayer film optical element.

In this optical element, the role of decision optical characteristics is not only born in the substrate of compositions such as glass, but also absorbing light, so that substrate must approach as much as possible.Therefore, after forming, also these substrates are polished multilayer film traditionally, thickness is remained down to about tens microns.

But it is extremely difficult the substrate of compositions such as glass being polished to about tens microns thickness, and exists owing to the problem that during the polishing infringement of glass is reduced output.

For example a kind of in Japanese patent application JPH3-196001 do not have the multilayer film optical thin film of described substrate to be known as a kind of optical element that solves the problems referred to above.

The manufacture method of this multilayer film optical thin film is as follows: for example, and deposition of aluminum film on substrate of glass, and on the top of this aluminium film, alternately form silicon oxide film and thin film of titanium oxide by ion sputtering.If by aluminium etching solution dissolved aluminum, then substrate of glass is separated with multilayer optical film, so that can obtain not have the multilayer optical film of substrate of glass when film formation is finished.

But,, find in the method for the multilayer optical film of making the described type of Japanese patent application JP H3-196001, to exist very big problem as the result of experiment that the inventor carried out.That is to say, in situation, in the projection of generation at the interface and the depression of aluminium and multilayer optical film by formation multilayer optical films such as ion sputterings; As a result, multilayer optical film is smudgy, causes light transmission significantly to descend, so that this optical thin film can not stand actual use.In addition, find that also aluminium can not fully take on the role of carrier, separate incomplete problem with multilayer optical film so that run into substrate of glass.

Summary of the invention

The present invention designs under these situations; The object of the present invention is to provide a kind of method of making the multilayer film optical element, this method makes and can prevent smudgy in the multilayer optical film, and separation of glasses substrate and multilayer optical film neatly.

Be used to realize that first invention of above-mentioned purpose is a kind of method of making the multilayer film optical element, comprise step: the film that in substrate, forms soluble carrier; On the top of this soluble carrier, form multilayer optical film; Dissolve the film of soluble carrier subsequently, make substrate separate with multilayer optical film, wherein soluble carrier is an aluminium, and the thickness of this soluble carrier is made as 10～90nm.

According to the ambiguous causal investigation result of multilayer optical film as mentioned above, the inventor concludes: the heat that produces when forming multilayer optical film owing to ion sputtering constitutes the crystallization again of the aluminium of soluble carrier; As a result, projection of generation at the interface and depression between aluminium and multilayer optical film, this causes producing smudgy.The inventor continues further investigation and finds: this uneven state changes according to the thickness of aluminium lamination, and if the thickness of aluminium lamination be 90nm or following, ambiguous problem does not then appear.

The inventor finds that also the reason that can not finish neatly of separating of substrate and optical thin film is: the thickness of aluminium lamination is too small, produces and does not form the part of aluminium lamination, and exist substrate and multilayer film directly to be bonded in the situation of these parts.Find in a large amount of experiments back: if the thickness of aluminium lamination be 10nm or more than, then this problem does not just take place.

Therefore, in the present invention, be limited to the scope of 10～90nm as the aluminum layer thickness of soluble carrier.The thickness here refers to mean value.

Second invention that is used to realize above-mentioned purpose is based on first invention, and the step that wherein forms multilayer optical film is the ion sputtering step.

Forming by ion sputtering in the situation of multilayer optical film, the temperature of aluminium lamination rises big especially, so that the effect of first invention is good especially.

The 3rd invention that is used to realize above-mentioned purpose is based on first invention or second invention, and wherein multilayer optical film is alternately laminated and form by niobium pentaoxide membrane and silicon oxide film, and the material that is formed directly in the film on the soluble carrier is a monox.

Forming in the situation of optical thin film by stacked niobium pentaoxide membrane and silicon oxide film, if the niobium pentaoxide film is formed on the aluminium, then the rising of temperature causes niobium pentaoxide and monox reaction, so that form aluminium oxide.Because aluminium oxide is the substance dissolves of dissolved aluminium not, so the peel property of substrate and multilayer optical film weakens.On the contrary, if silicon oxide film is formed directly on the aluminium, then can prevent this problem.

Be used to realize that the 4th invention of above-mentioned purpose is a kind of multilayer film optical element, wherein alternately form layer with different refractivity, and remove substrate during manufacture, the surface roughness Ra of wherein facing the optical surface of multilayer film optical element is 3nm or following.

Utilize the present invention, can obtain there is not the Ra that makes of substrate the very first time is 3nm or following optical filter, so that a kind of optical filter extremely low to the transmitted light loss can be provided.

Description of drawings

Fig. 1 is a sketch of making the method for multilayer optical film in the expression embodiment of the invention.

Implement optimal mode of the present invention

As shown in Figure 1, on substrate of glass (BK7) 1,form aluminium film 2 by vacuum evaporation, and on thisaluminium film 2, form the multilayeroptical film 3 that constitutes by structure shown in the table 1 that the film gross thickness is about 30 μ m by the ion sputtering method and (save description the 7th layer～107 layers, because odd-level is identical with layer 5, even level is identical with layer 6).Afterwards, this parts are cut into pieces by cutting, and again by NaOH solution etchingaluminium film 2, so that substrate ofglass 1 is separated with multilayer optical film 3.Substrate in the mirror status is as substrate ofglass 1, and surface roughness Ra is 0.2～0.4nm.

(table 1)

Level number	Material	Refractive index	Film thickness (nm)
				1	SiO2	1.46	265
2	Nb2O5	2.23	336
				3	SiO2	1.46	215
4	Nb2O5	2.23	135
				5	SiO2	1.46	215
6	Nb2O5	2.23	123
				…	…	…	…
…	…	…	…
				…	…	…	…
108	Nb2O5	2.23	170
				109	SiO2	1.46	253
110	Nb2O5	2.23	174
				111	SiO2	1.46	265

That table 2 expression gained multilayeroptical film 3 takes place is smudgy, multilayeroptical film 3 and the peel property ofsubstrate 1 and the relation between the aluminium film thickness.

(table 2)

Al thickness	Fuzzy	Peel property
			5nm	Do not occur	Impossible
10nm	Do not occur	Well
			90nm	Do not occur	Well
100nm	Occur	Well

Find out from the result of table 2,, then in multilayer optical film, do not occur bluring, and the stalling characteristic of multilayer optical film and substrate is good if the aluminium film thickness is 10～90nm.In addition, when the aluminium film thickness was 90nm, the surface roughness Ra on the aluminium film side of multilayer optical film was 0.4nm, and when the aluminium film thickness was 100nm, this surface roughness Ra was 1nm.And etching period is 40 hours when the aluminium film thickness is 10nm, but when the aluminium film thickness was 5nm, it was impossible peeling off fully.

Then, the roughness that is formed at the multilayer optical film on the aluminium lamination being measured surface roughness Ra is 0.4nm.As the result of this measurement, find that the surfaceness on the top layer on a side opposite with the aluminium lamination side is 3nm.Usually, in the film that forms by vacuum vapor deposition method, the surfaceness of film increases and increases along with the film gross thickness.

But, in the multilayer optical film of the embodiment of the invention, not only confirm less than fuzzy by visual observation, and even on roughness is considered to the highest surface, also can realize can with the comparable surfaceness of traditional optical filter with substrate.

By the way, the surface on the surface of aluminium lamination side and the top layer on a side opposite with the aluminium lamination side becomes the optical surface that light beam passes through.By realize minimum roughness on these optical surfaces, the effect that reduce the wastage required at the optical filter that is used for optical communication further enlarges.In addition, obtain surface roughness Ra by measure 10 μ m * 10 μ m zone with atomic force microscope in the present embodiment.

Thereby, because the surface roughness Ra of non-substrate optical filter is 3nm or following in the scope of 100 μ m2, thus can obtain not have substrate transmitted light is not almost had the optical filter of loss.

Next, utilize the method be similar to said method to form multilayer optical film, but do not form first tunic shown in the table 1, form Nb so that be made as respectively at the aluminium film thickness on the aluminium film of 10nm and 90nm₂O₅Film.

As a result, the etching of being undertaken by NaOH solution all can not be carried out well in either case, and the peel property of substrate and multilayer optical film is very poor, so that can not obtain to stand the multilayer optical film of actual use.

Claims (4)

1. a method of making the multilayer film optical element comprises step: the film that forms soluble carrier in substrate; On the top of this soluble carrier, form multilayer optical film; Dissolve the film of soluble carrier subsequently, make substrate separate with multilayer optical film, wherein soluble carrier is an aluminium, and the thickness of this soluble carrier is made as 10～90nm.

2. the method for manufacturing multilayer film optical element as claimed in claim 1, the step that wherein forms multilayer optical film are the ion sputtering steps.

3. the method for manufacturing multilayer film optical element as claimed in claim 1 or 2, wherein multilayer optical film is alternately laminated and form by niobium pentaoxide membrane and silicon oxide film, and the material that is formed directly in the film on the soluble carrier is a monox.

4. multilayer film optical element wherein alternately forms and has the layer of different refractivity, and removes substrate during manufacture, and the surfaceness of wherein facing the optical surface of multilayer film optical element is 3nm or following.

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